solo1 Posted November 8, 2012 Share Posted November 8, 2012 ello' scholars, for our midterm project were required to do an engine piston and crank assembly. I've finished all the pieces required but the 3 cylinder crankshaft. From the picture, I've started from the "B" side and will go to "A" then C eventually. After drawing and extruding the first 2 cylinders on the end, its time to do the ellipse at a 45 degree angle downward to the right. I don't know exactly how to use the ellipse dimensions given to make the part accurate. As of now, I manually drew 2 circles at a 39 mm apart from eachother then created my ellipse around it. Any tutorials or help would be lovely. my attempt: Quote Link to comment Share on other sites More sharing options...
Bishop Posted November 8, 2012 Share Posted November 8, 2012 You already appear to have done it the way I'd do it ... why can't you just do the same thing again? Quote Link to comment Share on other sites More sharing options...
solo1 Posted November 8, 2012 Author Share Posted November 8, 2012 I could do it again, but I dont believe it is dimensionally accurate. Is it really that simple? From the top right diagram you see that in the ellipse, the 2 cyclinders in each ellipse are overlapping eachother a bit. Each cylinder's diameter is 39. I figured the 25.5 minor, and 36.5 major dimensions would be relevant to creating the ellipse, but I didn't use that at all. What is the signficance of these 2 dimensions? Quote Link to comment Share on other sites More sharing options...
JD Mather Posted November 8, 2012 Share Posted November 8, 2012 The dimension is a bit of a fudge do to rounding off for drawing board. (we couldn't make perfect geometry back then) In a CAD program you can make the ellipse Tangent for blend into cylinder. Attach your file here and then I'll attach my solution. (oops - I just realized my rod journals are not 120° apart. I'll need to fix that.) This is the only example I have that is a good and ligitimate use of Move Face and also good use of Rotate Body. Quote Link to comment Share on other sites More sharing options...
JD Mather Posted November 8, 2012 Share Posted November 8, 2012 (edited) Well that was fun. I noticed your sketches aren't constrained - you might start here http://home.pct.edu/~jmather/skillsusa%20university.pdf Your Chamfer is in the wrong location as well. Oops - still wrong, back in a few. now i have it Edited November 8, 2012 by JD Mather Quote Link to comment Share on other sites More sharing options...
solo1 Posted November 12, 2012 Author Share Posted November 12, 2012 Mather, I think I've got it. I used constraints this time. Someone please correct me on my set-up if there's an error.. Quote Link to comment Share on other sites More sharing options...
solo1 Posted November 12, 2012 Author Share Posted November 12, 2012 (edited) whoops made a mistake last time.. correct one ^^^ Edited November 12, 2012 by solo1 Quote Link to comment Share on other sites More sharing options...
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